Practice question

A speed study conducted on a roadway segment collected the following data: 200 vehicles observed with a mean speed of 42 mph and a standard deviation of 5 mph. What is the 85th percentile speed assuming a normal distribution?

  1. 42.0 mph
  2. 44.5 mph
  3. 47.2 mph
  4. 52.0 mph

Answer: C — 47.2 mph

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